Separating solid particles



April 9, 1935. s. E. T. EWING ET AL.

SEPARATING SOLID PARTICLES 2 Sheets-Sheet l p i 1935. s. E. T. EWING ET AL 1,997,514

SEPARATING SOLID PARTICLES Fil d Nov. 1, 1953 2 Sheets-Sheet 2 \6 38 5o 42 52 39 474 OOOOGO surface. The troughcharges or' someof'them' charge.

Patented Apr. 9,. 1935 uNIrso 'srAT-E'sf ,SEPARATING soup PARTICLES swim? Edward a Ker Ewing and Joseph Leon-A V ard Willey, Jqhannesburg, TransvaahU t V V South Africa f i I 1 App lic a tion'November 1,.1933,s..ia1 N's. 696,260. In Unionof South Africa. November 3, 1932 I 13 "claim -"1 (01 209429) 7 The'present invention relates totheseparation of solid particles, such asparticles of ground ore and the like, according totheirdifierent settling tendencies in. a fluid, v i

. According to thisinvention, themixed material is supported; upon a flexible sheet in which is generated a'procession of waves without displacement of the sheet as a whole. :The waves are such that each wavetrough carries acharge of the material which remains within iand is transported by its trough as the lattermoves .forward. Owing to thefsheet beingstationary; in the direction ,of procession, the, transportation is accompanied by a rolling movementfof the trough charge over itself; whereby its particles are. agitated and. constantly. re-exposed at the are meanwhile exposed to the influence of aqfluid underconditions such that the particles of lesser settling tendencyaareremoved from the trough charge may be removed bythe wave movement V out of the influence of the fluid. 1

. The invention is illustrated inlth e accompany ing drawings in which:

- :Figurel is a perspective view of; a mechanical classifier embodying the invention.

Figure II shows a portionof the flexible sheet, in plan. V v Figures 111 andIV illustrate a method of manufacturing the flexible sheettof the classifier. 1 Figure V isa longitudinalelevation ofa table concentrator with parts broken away;

Figure V1 is an end view sectioned on -VI--VI FigureV. i t Figure VII is a half plan of Figure .V.; I

Theapparatus shown in Figure Iresembles the l well known mechanical classifiers in that .it com prises a. tank Zinto which pulp to be separated is fed from a supply-conduit 3;. the liquid carry-.

ing slime, (or themorebuoyantparticles) passing away by way of the overflow'l p whilst the sand constituent of the pulp, which settles through the liquid, is worked up. the] sloping floor 5 and discharged at the upper. end-6 thereof into the launder 1.

The modification of such .apparatusefl ected by the present invention resides inthe sloping floor and the manner-in which the sand is worked up it. The floor consists of flexible sheet material 5,

suchas sheet rubber, secured in 'atwater-tight manner to the walls "of the tank. For this pur pose its longitudinal edges 8 are shown as clamped between cleats i3 on the side walls l0. Its lower end; H is turned up and secured'to the mounted in thebrackets 16. The rollers 15 rest The particles remaining in the-trough and which is laterallydefined by lines v23. The

the centralzone 22; and said edges 8 are connectboards l2 so that-said boards and said turned up end form the third; wall of the'tank, the turned up end providing a flexible lower portion of said third wall on which the waves are initiated.

' Thefiexible sheet '5 is supported, and the waves 5 I3, 14 are produced-in it by a series .of rollers l5 on which the sheet freely rests and which extend across the. sheet. Said rollers are spaced apart and translated, by being: journalled in brackets l6 extending from the links of a pair of endless chains ll mountedon sprockets 18; the latter being rotated, the direction indicated "by the arrow A to: cause. those rollers which are carried incline. l i

The support gfor.:.said rollers is. provided by. a

bytheupper-spans of the chains, to travel up the 'pairqof inclinedtraoks ,20. On these tracks run pairs of track rollers12t, onepairior each roller l5.,sSaid trackrollers 2| .are,like the rollers l5,

freely uponthe trackjrollersz their journal holes inthe brackets "5 being elongated to permit this. The sheet 5 is extended upwardwell beyond the tank: properand its upper end ,6 is fixed to the chute-l9. Q. l g :In order topermit thewaves 13, M to be produced. without stretching the rubber'and without restraint by the clamped edges 8 of thesheet, the sheet is formed witha central zone 22 which is as long as the developed length of the series of waves extreme longitudinal edges 8 of the sheet, which are "secured to thesideawalls l0, are asv long. as said side walls andathus'considerably shorter than edges-8,; the distance between the arc 26axand the l to the developed length of the central zone. The

annular pieces 24a are securedlon'e at each side of the rectangle 22a and with theirlong edges 25 drum and the annular piecesi ia, are held against the respective end faces'of the drum. The corners 28 of the drum are rounded to a small radius to enable the edges of the pieces 2% and 22a to be butted against one another. Said edges are united by cementing or the like; and the completed assembly, being removed from the drum, becomes the sheet 5; the piece 22a'constituting the central zone 22 and the pieces 24w constituting the lateral zones 24. In order that'the waves may effectively transport the material lying in their troughs [4, it is necessary for the wave fronts 29 to be distinctly steeper than the angleof repose of the material on the rubber. To enable such steep wave fronts to be produced, the central zone 22 ismade of such length that whenthe wave crests 13 are shaped by the rollers 15, the troughs M are distinctly baggy. The steepening is assisted, and undesirable depth of the troughs avoided by causing the lower ends of the troughs "to rest on fixed-decking 30 so that each trough hasa flat base from which the wavefront 29 rises at asharp angle.

For the purpose of retaining this baggy formation of'the troughs and to prevent-'bcdily displacement of the loose central zone, it is necessar'y that the rollers 15 should not bemerely pushed beneath the sheet but should have a true rolling motion against the iower facathereof. D ue to the extra length of 'the centralzone-22' over the directlength of the floor, the'rollers have so to rotate that while, their translational displacement is equal to the length of the floor, their peripheral displacement equals the developed length of the central zone22. This is brought about by making the diameter of their treads3'l, which rest upon the track rollers 2 I, less than-the diameter of the roller surfaces in the ratio of the direct length of thesheetto the developed length of its central zone 22, in other words in the same ratio as the arcs 2'5and 25a.

. In operation the tank contains pulp up to the level indicated by the line 32, which isthetrace of the pulp surface m the, wall 19. Fresh pulp being'fed from launder 3, and the chain and roller mechanism being in operation, the puip is kept in :a state-oi" agitation which causes slime or the lighter material to remain in suspension in the liquid. Liquid is constantly displaced' by theVincoming pulpv and flows away over lip 4, carrying slime with it. 1 I The waves on the .sheetbegin' at the lower end of the floor due to the travelling roller 15 coming into contact with thefloor-at that point; and thus travel in a constant succession to the upper end 6 of the flooig where they disappear owing to the rollers lipassing around the upper sprockets and so away from the floor.

The sand constituentof the pulpsettles in those nozzles 33.

. gitudinally.

while the trough charges travel over it in that direction, said charges are rolled over the surface. In this way they are kept in a state of agitation which prevents their compacting; and

fresh. surfaces of them are constantly exposed.

This permits slime to continue to separate from the sand and to enter into suspension in the pulp while the charges are within the tank. It also renders the charges which have passed out of the tank readily susceptible to washing by Wash. water delivered for instance from spray Such wash water tends to flowalong the troughs transversely to the length of the floor and so reach the. side channels 34 at the junction of the fioor with the side walls l 0, down which side channels it is free to flow back to the tank without -re-contaminating the lower trough charges.

In this way the waved floor tends to clean separation of sand and slime. It will be observed that mechanism subject tor wear is whollyexternalof the tan-k and not in contact with the pulp in any-way. It is thus protected against the rapid wear-which occurs at the joints and other vulnerable parts of meehanism when working submerged in pulp.

' The concentrating table shown in Figures V to VII comprises an apron 35 secured along a central line to a longitudinal bar 36 supported by hangers 3'! from the cross members 38 of the frame'of thetable. The'table is, in the example shown; duplicated on each. side of said central line.

apron is unattached and both the wings of it -rest loosely on the upper span of an endless series pf spaced rollers 39 carried by the chains 48 waves each consisting of a crest 42 and a trough Except where it is secured to the bar 36, the V 43; extending transversely tothe length of the apron. i

The troughs preferablyincrease in depth from the centre of the table towards each longitudinal edge thereof; and the apron is 'pre-formed to 3 enable it' to take this form ;without being stretched. That is to say each wing of the apron is out as a part of an annulus of which the inner edge is equal to the length of the bar 36 and its outer edge equal in length to the developed'leng'th of the outer edges of the apron. Said annular pieces are secure'd'to the bar 36 by their short edges. The troughs of the waves are, as in the classifier, bass? and loose; similarly, the rollers 39 are so rotated on their own axes and tapered towards their mid points that they lift and lower the apron loosely without transporting itlon:

For this purpose there are provided the track rollers 45 'mounted on the chain brackets 46 which carry the rollers 39. and running on the tracks 41. I Fast with each roller 45 Ba me: tion wheel 48 of' larger diameter whichengages with and rotates a tread 48 on the adjacent roller 39. In, this'way transportation of the farther end fil'of the apron. Meanwhile the trough charges are turned over-andconstantly exposed to fluid flowing fromthecentre or: the table towards its edges 44. Suchflowing fluid may be jets of air,'if the material'is dry; or water when the material is in the form of p lp; The pulp may be originally-ted in asuflicient-ly dilute condition to itself provide} the requiredlateralv 'flow of water; i or additional wash -water 'may be supplied as from nozzles 52;- Thetroughcharges' are thus given a second 'motionalongfthe troughs outwardly, due to the flowingfluid assisted by the slope of the troughs.- The specifically lighter and less valuable gangueymaterial' is most influenced in this way and is passed ofi the apron at an early stage of'the operation, into say a waste launder 53. The specifically heavier con-E stituents of thepulp mostresist the' washing and gravitational action and's'oare man discharged into a concentrate launder" 54 situated at or towards the'end 5| of the table; Aninterni'ediat'e grade of material may be collected ina middlings launder 55. i

1. Apparatus for" separating solid particles,

comprising a flexible sheet which so anchored as to be immovableas a whole and wlnchHspf non-uniform developed linear extent in the di rection of the translation-of the rollersnieans to produce a succession of material transporting and agitating waves in'said sheet comprising a series of spaced rollers on-which the sheet loosely rests, means to translate them transversely of their length successively beneath the sheet; together with means to subject material in the wave troughs to fluid in motion so as to remove particles of lesser settling tendency from the troughs.

2. Apparatus for separating solid particles,

comprising a fixed framework, a flexible sheet including a relatively short longitudinal zone fixed to said framework, and including also a relativelylong longitudinal zone so arranged that it occupies the same rectilinear extent as i the short zone and thus assumes a baggy condition, means to produce a succession of materialtransporting and agitating wavesmoving continuously in one direction only longitudinally in said relatively long zone of the sheet, means to cause deposition of material in the troughs ,of

said waves, and means to subject material in the wave troughs to fluid in motion.

3. Apparatus for separating solid particles comprising tank walls providing an overflow lip, an inclined flexible sheet constituting the floor of the tank and extending upward above the overflow 1ip, means to produce in said sheeta succession of material-transporting and agitating waves moving longitudinally and upwardly of the sheet, and means to introduce pulp to be separated into the tank. v e 4. Apparatus for separating solid particles comprising tank walls providing an overflow lip, an inclined flexible sheet constituting the floor of the tank and extending upward above the 'overflowlip, means'to. produce in said sheet a succession of material-transporting and'agitating waves,1moving longitudinally and upwardly of the sheet,' means to introduce pulp to be 'sep arated into the tank; and means for discharging wash liquid into the wave I troughs above the overflow lip. l

" 5. Apparatus for separating "solid particles,

co'rnprisingtank walls providingan overflow lip, an inclined flexible sheet constituting the; floor of the tank and extending upwardbeyondthe overflow lip,- said sheet having relatively; short longitudinal edge zones fixed to the tank structure and a relatively *long central longitudinal zone puckered to occupy the same" length as the ing and agitating waves: therein, and means to introduce'pulp into the tank;

6; Apparatus as cla medm claim' 11, which in-- eludes means to-feed wash liquid to the troughs 7 above the overflow lip, and in which the flexiblesheet" provides longitudinal drainage channels at the junction edge'jzones'; A

"7. Apparatus for 'separating" solid particles,

comprising tankwalls providing an overflow lip,

of central zone with the edge portions, means contacting with} the rela- H 'tively long central zone of the'sheet to produce a series of upwardly mo ving material-transportairincliriedflexibl sheetconstituting the floor 'ofthetank; and extending upward beyond the overflow lip, said sheet having relatively short longitudinal edge zones fixed to straight portions of the tank structure, said sheet also having a central longitudinalzone of greater developed length than the edge zones and occupying the same direct length as the latter, a series of cylindrical rollers moving beneath the central zone to form a series of upwardly moving waves therein, means for positively rotating said roll-' ers on their individual axes so that they have rolling contact with the sheet, means so "supporting the troughs of the waves as to cause the waves to be steep-fronted, and means to introduce, the pulp into the tank. a

8. Apparatus for separating solid particles,

comprising a horizontally disposed flexible sheet I which is anchored against bodily movement,

means-to feed material to be separated onto a corner at one endof the sheet, means to produce, .in the sheet a series of material-transporting and agitating waves moving away from said end and extending transversely of the sheet to an edge thereof, and a series of stationary launders arranged for selectively receiving material discharged from the edging of the sheet'distant from the feeding corner. i

9. Apparatus for separating solid particles,

' comprising a horizontally disposed flexiblesheet which is anchored against bodily movement,

corner.

1 0. Apparatus for separating solid particles, comprising a framework, a flexible sheet varying transversely as regards its longitudinaldeveloped i length, the shortest developed length being-arranged. in a horizontal plane and fixed .to the framework, means toproduce in said sheet a series of transverse waves increasing in depth from said shortest-length to an edge of the sheet and moving in one direction only longitudinally of the sheet, means to feed material to be separated onto the sheet at one end of said shortest length and aseries of stationary launders arranged for selectively receiving material discharged from the edging of the sheet distant from the feed point.

11. Apparatus for separating solid particles,

7 comprising a framework, a flexible sheet varying transversely as regards its longitudinal developed length, the-shortest developed length being arranged in a horizontal plane and fixed to the. framework, a series of conical rollers supporting and'moving beneath the sheet in one direction only and forming thereina series of transverse waves increasing in-depth from said shortest length to an edge of the sheet and moving in said one direction only longitudinally of the sheet,

means to feedmaterial to be separated onto the sheet atone end of said shortest length and a series of stationary launders arranged for se1eo tively receiving materal discharged'from the edg ing of the sheet distant from the feed point.

12, Apparatus for separating solid particles, comprising a framework, a horizontally disposed flexible sheet anchored to the-framework against bodily movement, means to feed material to be a separated onto a corner of the sheet at one end arranged transversely to and supporting the sheet so as to form a series of transverse waves thereinfmeans. for traversing said rollers continuously in one direction beneath the sheet,

13. Apparatlis for separating solid particles, comprising a flexible sheet, a pair of endless chains extending longitudinally of the sheet, means to propel the chains, brackets extending from links of the chain, sheet supporting rollers carried by said brackets and so supporting the sheetas to-form therein a series of materialtransporting and agitating waves, a fixed track,.

and track rollers carried by the brackets and rolling on said track as the chains are propelled,

said track rollers rotating the sheet supporting e rollers at a peripheral speed greater than their own. i I

SYDNEY EDWARD THACKER EWING.

JOSEPH LEONARD WILLE-Y'.

thereof distantfrom an edge, a series of'rollers V 

